PIF2025 - BREAK2ADAPT_Annelid_genomics - (PID2024-161173NB-I00)

The transition of animals from marine to terrestrial environments represents one of the most significant evolutionary events, necessitating extensive physiological, morphological, and genomic adaptations. While research has traditionally focused on gene-centric modifications, emerging evidence highlights large-scale genomic rearrangements as key drivers of adaptation. In clitellate annelids (earthworms, leeches, and their relatives), extensive chromosomal restructuring, termed genome atomisation, has coincided with the transition to terrestrial habitats. This process involves widespread fragmentation and reorganisation of ancestral linkage groups, disrupting macrosynteny and reshaping the 3D genome architecture. These alterations may have facilitated the emergence of novel topologically associating domains (TADs) and regulatory interactions critical for terrestrial adaptation. The BREAK2ADAPT project seeks to uncover the timing, mechanisms, and functional consequences of genome atomisation in clitellate annelids. By integrating comparative phylogenomic analyses, high-resolution chromatin architecture data, and experimental approaches, we aim to: (i) determine when genome atomisation occurred, (ii) investigate the mechanisms driving chromosomal breakage and reorganisation such as transposable element mobilisation, chromoanagenesis, and DNA repair failures, and (iii) explore how these genomic changes facilitated adaptation to freshwater and The transition of animals from marin